Apparatus for reconditioning insulating mediums



mman @C 225Q722 .4.; 2, 1941. L. E. sAul-:R 2,264,722 k* 'y 'vl/'lAAPPARATUS FOR RECONDITIONING INSULATING MEDIUMS Filed Jan. 18, 1939 2Sheets-Sheet l mmm 2, 1941. L. E. sAuER 2,2541722 APPARATUS FORRECONDITIONING INSULATING MEDIUMS Filed Jan. 18. 1939 2 Sheets-Sheet 2*lon-iat,

..ftaria lieu.

APPARATUS FOR RECONDITIONING INSULATING MEDIUMS Louis E. Sauer, Sharon,Pa., assigner to Westinghouse Electric & Manufacturing Company, EastPittsburgh, Pa., a corporation of Pennsylvania Application January 18,1939, Serial N0. 251,567

7 Claims.

This invention relates to apparatus for the reconditioning of insulatingmediums and particularly for the reconditioning of chlorinated cyclichydrocarbon insulating mediums.

Chlorinated cyclic hydrocarbons containing a freezing point depressorare employed as the noninflammable insulating and cooling fluids intransformers, capacitors, circuit breakers, regulators and otherelectrical apparatus. In practice it is necessary to treat theseinsulating mediums after they have been in service for given periods oftime to recondition them by removing impurities therefrom and restoringthe dielectric properties of the medium.

Different apparatus have been employed in an attempt to reconditionthese insulating mediums, but such apparatus have not always beensatisfactory because of the pressures necessary for effecting the now ofthe insulating medium therethrough, or the activated material such asactivated earth which is employed for restoring the dielectricproperties of the medium becomes packed or chaneled in the apparatus,and it is impossible to obtain the necessary uniform mixture of themedium and the activated earth.

An object of this invention is to provide apparatus for thereconditioning of insulating mediums whereby the activated materialemployed for the reconditioning is so retained in the apparatus that itwill not pack as the insulating medium ows therethrough.

Another object of this invention is to provide apparatus for thereconditioning of insulating mediums having a chamber having activatedmaterial so disposed as to prevent packing of the activated material andto provide a good mixing of the activated material with the insulatingmedium as the insulating medium passes therethrough.

A further object of this invention is to provide apparatus for thereconditioning of insulating mediums in which a container havingactivated material therein is so disposed that the insulating mediumpasses therethrough in a manner to effect a good mixing of the activatedmaterial therewith and to provide for the easy separation of theactivating material from the reconditioned insulating medium.

Another object of this invention is to provide apparatus for thereconditioning of insulating mediums in which the insulating medium ispassed upwardly through an activating material to effect a thoroughmixing therewith while providing for so changing the direction of flowof the insulating medium carrying the activated material as to free itof a major part of the activated material after which the insulatingmedium continues its upward flow and is freed of the balance of theactivated material.

A more specic object of this invention is to provide a barrier in acontainer having activating material therein and through which aninsulating medium is passed upwardly to so change the direction of nowof the insulating medium as to free it of a major part of the activatingmaterial after which the insulating medium is permitted to continue itsupward flow and the balance of the activated material is removedtherefrom to give a reconditioned insulating medium.

A still further object of this invention is to provide a compactapparatus for reconditioning insulating mediums formed from a pluralityof chambers disposed in spaced relation as inner and outer chambers, theinner chamber containing activated material, together with meansassociated with the chambers to induce the flow of an insulating mediumupwardly through the activated material in the inner chamber to effect athorough mixing therewith and to prevent its packing, while alsoproviding for retaining the activated material in the inner containerwhile permitting the insulating medium to flow from the inner containerdownwardly in the space between the containers and withdrawing it fromthe apparatus.

A more specific object of this invention is to provide apparatus forreconditioning insulating mediums in which a plurality of containershaving activating material therein and filters therebetween areassociated in assembled relation with a common header and connectionsthereto for permitting the insulating medium to effect a flow upwardlythrough the activating material in the containers, the containers havingmeans for retaining the activating material therein while permitting theinsulating medium to flow therefrom to the lters disposed between thecontainers, and a common header and connections thereto associated withthe lters for permitting the ow of insulating medium therefrom.

Other objects of this invention will be apparent from the followingdescription when taken in conjunction with the accompanying drawings, inwhich:

Figure 1 is a front elevational view embodying the apparatus in thisinvention;

Fig. 2 is a. side elevational View, partly in section, of the apparatusof Fig. 1;

Fig. 3 is a side elevation of another embodiment of apparatus embodyingthis invention;

Fig. 4 is an end elevational view of the apparatus shown in Fig. 3;

Fig. 5 is a side elevational view, partly in section, of a portion ofthe apparatus shown in Fig. 3, and

Fig. 6 is a sectional view of the apparatus embodylng this inventiontaken along the line VI-VI of Fig. 5.

Referring to the drawings and particularly Figs. 1 and 2 thereof, thisinvention is illustrated as applied to a reconditioner unit I forinsulating mediums such as the chlorinated cyclic hydrocarbons. In theparticular embodiment illustratedr'rthe unit I0 comprises a plurality ofcontainers I2 and I4 so disposed in spaced relation that the containerI2 forms an inner chamber having its side walls spaced from the sidewalls of the outer container I4. In assembling the container I2 and I4,the bottom of the inner container is spaced from the bottom of the outercontainer as by means of a gasket I6 disposed therebetween at the outeredge of the bottom of the inner container, and it is sealed about itsperiphery to provide a space I8 between the bottoms which is sealed fromthe space 20 formed between the side walls of the containers.

Since it is desired to pass an insulating medium through an activatingmaterial to recondition it, the inner container I2 is provided with ascreen bottom 22 as illustrated in Fig. 2 for normally retainingactivating material, not shown, within the inner container. Fullersearth, known as activated earth is preferred as the activating materialbecause of its broader reconditioning effect on the chlorinated cyclichydrocarbons. Other activating material such as activated carbon orcocoanut charcoal may however be employed while activated alumina isparticularly effective in removing moisture from the insulating mediums.The insulating medium is introduced into the sealed space I8 underpressure as will be explained more fully hereinafter, and flows upwardlythrough the screen bottom 22 of the container I2, and through theactivating material (not shown) retained within the chamber.

As there is a tendency for the insulating medium to carry some of theactivating material away from the container I2 as the insulating mediumows therefrom, a suitable cover 24 which will function to prevent thecarrying away of the activating material is provided for the containers.In a preferred embodiment, the cover 24 is formed from a plurality ofparts comprising spaced members 26 and 28 which are sealed about theirouter edges as at 30 and are of predetermined size to cover bothcontainers. The member 26 is a screen provided with openings 32 over thecontainer I2 and openings 34 disposed to register with the space betweenthe side walls of the containers I2 and I4. In order to prevent the owof the activating material in the insulating medium from the containerI2 as the insulating medium flows through the screen member 26, a filter36 of suitable material such as blotting paper is provided on the lowerside of the member 26 disposed to fit over and cover the top of thecontainer I2, and to seat on the lug or ring flange 38 carried about theinside top edge of the container I2. In this position with the openings34 registering with the space 20 between the side walls of thecontainers, the cover is securely held in position on the containers bymeans of suitable clamps such as the C-clamps 46 disposed .in spacedrelation about the outer container I4 and so pivotally carried thereonthat they can be actuated to seat on the cover 24 to securely maintainit in position with respect to containers I2 and lI4.

In order to withdraw the reconditioned insulating medium from the space20, suitable outlet connection 44 is provided near the base of thecontainers, the'outlet connection having a suitable valve 46 disposedtherein for controlling the -flow of the insulating medium away from thereconditioner apparatus. In addition to the outlet connection 44, thecontainers are provided with an air exhaust 48 disposed in the cover 24,the air exhaust having a float valve, not shown, therein for releasingair from the container as it becomes entrapped therein.

In order to carry the assembled containers I2 and I4, a suitable support50 is provided and the containers are so welded or otherwise securedthereto that they will comprise an integral unit. The support 50 has avertical extending portion 52 to which the containers are suitablyattached and a base portion 54 for carrying a suitable motor and pumpassembly 56 for delivering the insulating medium to the sealed space I8in the containers, Briefly, the motor and pump assembly 56 comprises themotor 58, the pump 60 and suitable connections thereto such as theintake connection 62 having an in-take valve 64 therein for connectionwith the supply of insulating medium which is to be reconditioned, thestrainer 66 through which the insulating medium is passed prior todelivery to the pump, and the connection 68 through which the insulatingmedium is delivered from the pump to the sealed space I8.

In order to safeguard the apparatus in case the pressures built up inthe reconditioner unit become too great, a relief valve I0 is providedin a connection 12, and will function upon predetermined pressure in thecontainers to by-pass the insulating medium directly from the connection68 back to the strainer 66. If the pressure in the apparatus to whichthe reconditioned insulating medium is delivered becomes too great,suitable connections I4 having a relief valve 16 therein is provided tofunction under predetermined pressures to by-pass the reconditionedinsulating medium directly from the space 20 between the side walls ofthe container back to the strainer and pump to effect the circulation ofthe insulating medium only through the reconditioner unit.

In operation, the insulating medium is delivered to the in-take valve 64and passes through the strainer 66 to remove any large particlestherefrom from whence it flows, as indicated by the arrows in Fig. 2,through the pump 60, connection 68 to the sealed space I8 between thebottoms of the containers. Since the insulating medium is delivered tothis space under pressure by reason of the pump 60, it passes throughthe screen bottom 22 of the inner container I2 and flows upwardlythrough the activating material normally contained therein. As theinsulating medium flows through the activating material, it is to benoted that the direction of flow of the fluid is opposite to the actionof gravity on the activating material. Such flow of the insulatingmedium through the activating material is suicient to so agitate theactivating material as to produce looseness of the activating materialand to effect a complete mixing of it with the insulating medium to givea substantially uniform distribution of the activating material in theinsulating medium in any given horizontal cross section of the containerI2. As the insulating medium flows upwardly in intimate contact with andthrough the activating material, the force of gravity causes theactivating material to tend to so lter out of the insulating medium,that by the time the insulating medium reaches the top of the insulatingcontainer I2, a major part of the activating material has becomeseparated from the insulating medium dropping towards the bottom of thecontainer Where it again is mixed with incoming insulating medium.

As the insulating medium freed from the major part of the activatingmaterial reaches the top of the inner container I2, it is ltered throughthe lter 36 where the last fine traces of the activatg material isseparated therefrom and the insulating medium ows through the opening 32to the space between the members 26 and 28 of the cover over to anddownwardly through the openings 34 and space 20 between the side wallsof the containers from which it is withdrawn through the connection 44and delivered in the reconditioned state to suitable storage tanks or tothe apparatus in which it is employed.

In another embodiment of this invention as illustrated in Figs. 3 and 4,the reconditioner unit comprises a plurality of containers I8 andfilters 80 mounted in assembled relation with the filters disposedbetween the containers. The assembled containers and lters are carriedin a suitable support 82 formed from the frames 83, end member 84 andside rods 86 and are retained in position between the side rods 86 andthe end frame 84 by means of the screw press assembly 88 which can bemanually operated to adjust the pressure on the assembled containers andlters to any predetermined amount. The support 82 also carries the motorand pump assembly 90 which assembly is somewhat similar to the assemblydescribed with reference to Figs. 1 and 2. Briefly, in this embodimentthe motor and pump assembly 90 comprises a suitable intake connection 92having an in-take valve 94 disposed therein connected through a strainer96 through the pump 98 and hence upwardly through the connection |00 tothe assembled containers and filters.

As illustrated, the reconditioner unit has a discharge outlet and valve|02 connected therein disposed adiacent the top of the containers.Similarly to the motor and pump assembly of Figs. 1 and 2, the apparatusshown in Figs. 3 and 4 also has a relief valve |04 and connectionsthereto for by-passing the insulating medium directly from thecontainers back to the pump when the pressure within the apparatus towhich the insulating medium is to be delivered becomes too great and arelief valve |06 and connections associated therewith for by-passing theinsulating medium around through the strainer 96 and the pump 98 insteadof delivering it to the container and filter assembly when the pressurewithin the containers becomes too great.

Referring to Figs. and 6 of the drawings, the containers employed inthis particular embodiment are illustrated in detail. The containers '|8are formed with the side walls |08 which are impervious to insulatingmedium and top and bottom walls I0 and ||2, respectively. As will benoted in Fig. 5, headers ||4 and I6 are provided in the top and bottomrespectively of the container and extend therethrough, these headersbeing common to all of the containers and iilters employed in theassembly unit.

Each of the containers 18 is provided with a sealed chamber I8 disposedin the bottom of the container and suitable connections |20 leading fromthe top header |4 downwardly through the container to the sealed bottomchamber. Thus the supply of the insulating medium as it is deliveredfrom the pump assembly to the container units is delivered to the commonheader ||4 and from there is directed to the sealed chamber ||8 in thebottom of the containers.

stemmer activated material, not shown, disposed therein above the sealedchamber ||8. Since it is desired to permit the insulating medium to flowthrough the activating material in order to recondition it, the chamber||8 is provided with a screen cover |22 which functions to retain theactivating material in the container while at the same time permittingthe insulating medium to ilow into and through the chamber containingthe activating material.

As the insulating medium flows upwardly under pressure through theactivating material, it carries a certain amount of the activatingmaterial therewith. In order to provide for separating a major part ofthe activated material from the insulating medium, a barrier |24 isprovided adjacent the top of the container and is so disposed as toextend substantially across the container. The barrier |24 is carried inany suitable manner by a screen plate |26 disposed across the top of thecontainer and is attached thereto as by means of bolts |28. In practicea lter |30, of suitable material such as blotting paper, is also mountedin the barrier assembly and is preferably so disposed across the lowerside of the screen plate 26 as to function to prevent the passage offine particles of the activating material through the screen |26.

As is illustrated in Fig. 6, the barrier |24 has downwardly extendingedges |32 so that as the insulating medium flows upwardly toward the topof the container, it strikesl the barrier |24, and because of theoutwardly and downwardly extending side edges |32, the direction of owof the insulating medium is so changed that by reason of the pull ofgravity a major part of the activating material is separated from theinsulating medium. As the insulating medium clears the downwardlyextending edge |32 of the barrier, it continues its upward iiow free ofthe major part of the activated material and passes upwardly and throughthe iilter |30 and the screen plate |26 to a chamber |34 providedthereabove.

Since it is possible that some of the ner activating material may becarried in the insulating material to the chamber |34, the filters 80are disposed between adjacent containers 18. The side wall |08 of thecontainer is provided with openings |36 near their top edge forpermitting the insulating medium to flow from the chamber |34 to thefilters 80. As shown in Fig. 6, the side walls |08 are secured to thetop ||0 and bottom ||2 of the container at a distance in from the outeredges of the top and bottom to provide a space between the assembledfilters 80 and the side walls of the container for permitting theinsulating medium to flow therebetween. The lters 80 are of standardconstruction being formed from the lter press plate |38 of any of thewell known construction and the sheets of lter paper |40, such as blot-The containers 'I8 are provided with a supply of 75 ting paper, disposedon either side of the lter press plate. As the insulating medium owsdownwardly along the side wall |08, it filters through the lter paper|40 and trickles down around the projections on the lter press plate |38to the bottom of the filter where it is discharged through suitableopenings |42 into the header ||6 which is common to all ofthe filtersdisposed between the container and extends therethrough the assembledunit formed from the containers and lters. Each of the filters in theassembly has the opening |42 provided therein for discharging into theheader I6 which is sealed from the containers 18.

In operation the in-take connection 92 is connected`to the apparatuscontaining the insulating which is desired to be reconditioned and thevalve 94 is opened to permit the insulating medium to flow from theapparatus through the strainer 96 to the pump 98 from which it is forcedthrough the connection into the cornmon header ||4 of the assembledcontainers and filters. As the insulating medium fiows through theheader ||4 a portion of the insulating medium is taken therefrom at eachcontainer and passed downwardly through the pipe |20 to the space ||8 atthe bottom of the container. From this space the insulating medium flowsthrough the screen |22 upwardly through the activating materialcontained in the chamber to effect a thorough uniform mixture therewith.As the insulating medium fiows upwardly it strikes the barrier |24 whichdeects the flow of the medium outwardly and downwardly, effecting aseparation of a major portion of the activating material carried thereinand permitting the insulating medium freed from the major part of theactivated material to flow upwardly around the outer edges of thebarrier |24 through the filter |30 and the screen plate |26 into thechamber |34. From this chamber the insulating medium which has beenfreed of the activating material fiows through the openings |36 andthrough the filters |40 to insure the removal of any remainingactivating material in the insulating medium into the spaces formedbetween the filter press plate and the filter and hence downwardly tothe return header ||6 from which the reconditioned insulating medium isreturned to the apparatus from which it was withdrawn.

By means of the apparatus constructed in accordance with this invention,insulating mediums can be reconditioned at very low cost. Further, theactivating material is eiiiciently employed since by passing theinsulating medium upwardly therethrough an ecient complete mixing andlooseness of the activating material in the insulating medium isobtained. Further separation of the activating material from thereconditioned insulating medium is easily obtained, since all of theinsulating medium must flow upwardly through the containers and, as itapproaches the top of the container, the upward movement of anyactivating material carried in the insulating medium is retarded byreason of the force of gravity thereon. Instead of being carried out ofthe container with the insulating medium, the activating material tendsto separate therefrom, and to eddy downward to the base of the containerwhere it is again recirculated and mixed with incoming insulatingmedium. Further, in the particular embodiment illustrated in Fig. 6,this natural tendency for the activating material to separate from theinsulating medium is aided by means of the barrier positioned across thetop of the container for deflecting the flow of the insulating mediumand thereby permit the separation of the major part of the activatingmaterial by reason of the force of gravity. This apparatus is alsoconstructed in comparatively small units by providing the screened topfor the containers for retaining the finer portion of the activatingmaterial in the container instead of constructing containers so large asto permit the force of gravity .only to effect the complete separationof the activating material in the insulating medium.

Although this invention has been described with reference to particularembodiments thereof, it is, of course, not to be limited thereto exceptinsofar as is necessitated by the prior art and the scope of theappended claims.

I claim as my invention:

l. Apparatus for the reconditioning of liquid insulating mediumscomprising, in combination, a container, activating material disposed inthe container, means for admitting the insulating medium which is to bereconditioned into the bottom of the container, means associated withthe container for forcing the insulating medium to flow upwardly againstand through the activating material thereby agitating the activatingmaterial and insuring the mixing of the activating material with theinsulating medium whereby the activating material reconditions theinsulating medium, a bafiie disposed in the container adjacent its topfor changing the course of flow of the insulating medium to free it of amajor part of the activating material carried therein, the baiile beingconstructed and arranged in the container to allow the upward flow ofthe insulating medium after it is freed of the major part of theactivating material, and means disposed above the baliie forsubstantially freeing the insulating medium from the balance of theactivating material while permitting the insulating medium to flow fromthe container.

2. Apparatus for the reconditioning of liquid insulating mediumscomprising, in combination, a container, activated earth disposed in thecontainer, means for admitting the insulating medium which is to bereconditioned into the bottom of the container, means associated withthe container for forcing the insulating medium to fiow upwardly againstand through the activated earth thereby agitating the earth and insuringthe mixing of the earth with the insulating medium whereby the earthreconditions the insulating medium, a barile disposed across thecontainer adjacent its top for directing the flow of the insulatingmedium containing the activated earth towards the side walls of thecontainer, means adjacent the edges of the baille for permitting theinsulating medium to flow around the edges and above the baule, and afilter disposed above the bailie for permitting the flow of theinsulating medium from the container, the baiile and filter cooperatingin retaining substantially all of the activated earth in the container.

3. Apparatus for the reconditioning of liquid insulating mediumscomprising, in combination, a plurality of containers, a plurality offilters associated in assembled relation with the containers, aplurality of headers common to the containers and filters, a pluralityof screen filters disposed in each of the containers across it andadjacent its top and bottom, activated earth in each of the containersand retained therein by the top and bottom screen filters, means foradmitting liquid insulating medium under pressure into one of saidheaders, means associated with each of the containers and with said oneof the headers for admitting a portion of the insulating medium into thecontainer below the bottom screen filter thereof, the insulating mediumunder pressure being forced upwardly therefrom against and through theactivated earth retained between the screen filters thereby agitatingthe earth and insuring the mixing of the earth with the insulatingmedium to recondition the insulating medium, means for permitting theinsulating medium to ow from the container to and through the filtersassociated in assembled relation therewith, and means associated witheach of the lters and said other header to permit theiow of thereconditioned insulating mediurn into said other header whereby it mayow from the apparatus.

4. Apparatus for the reconditioning of liquid insulating mediumscomprising, in combination, a plurality of containers, a plurality offilters associated in assembled relation with the containers, aplurality of headers common to the containers and filters whenassembled, one of said headers being disposed adjacent the top of thecontainers and filters, another of said headers being disposed adjacentthe bottom of the containers and lters, a plurality of screen filtersprovided in each of said containers across it and adjacent its top andbottom, activated earth in each of the containers and retained inposition by the top and bottom screen filters, means for admitting asupply of the liquid insulating medium under pressure to the top header,means in each of the containers for carrying the insulating medium fromthe top header into the container below the bottom screen filter, saidinsulating medium under pressure being forced to flow upwardly againstand through the bottom screen filter and activated earth therebyagitating the earth and insuring the mixing of the earth with theinsulating medium to recondition the insulating medium, the top screenlter retaining the activated earth in the container as the insulatingmedium ows therethrough, means for admitting the insulating medium fromthe container to the lters associated in assembled relation therewith toinsure removal of impurities, and means for admitting the reconditionedinsulating medium from the filters into the bottom header which iscommon to the lters whereby it may flow from the apparatus.

5. Apparatus for the reconditioning of liquid insulating mediumscomprising, in combination, a plurality of containers, a plurality offilters associated in assembled relation with the containers, aplurality of headers common to the containers and lters, a plurality ofscreen filters disposed in each of the containers across it and adjacentits top and bottom, activated earth disposed in each of the containersand retained therein by the top and bottom screen filters,

means for admitting liquid insulating medium under pressure into one ofsaid headers, means associated with each of the containers and with saidone of the headers for admitting a portion of the insulating medium intothe container below the bottom screen lter thereof, the insulatingmedium under pressure being forced upwardly therefrom against andthrough the activated earth retained between the screen filters therebyagitating the earth and insuring the mixing of the earth with theinsulating medium to recondition the insulating medium, means disposedin the container adjacent its top but below the screen filter forchanging the course of flow of the insulating medium to free it of amajor part of the activated earth carried therein, said means permittingthe upwardly flow of the insulating medium after it is freed of themajor part of the activated earth through the top screen lter, means forpermitting the insulating medium to ow from the container to and throughthe lters associated in assembled relation therewith. and meansassociated with Examiner each of the lters and said other header topermit the flow of the reconditioned insulating medium into said otherheader whereby it may flow from the apparatus.

6. Apparatus for the reconditioning of liquid insulating mediumscomprising, in combination, an outer container, an inner containerdisposed in spaced relation in the outer container to provide a spacebetween the bottoms and side walls thereof, means for sealing the innercontainer around its bottom to the bottom of the outer container toprovide a space therebetween which is sealed from the space formedbetween the side walls of the containers, means for admitting liquidsinto the sealed space, a screen disposed across the bottom of the innercontainer above the space formed between the bottoms of the containersfor permitting liquids to ow therefrom into the inner container,activated earth disposed within the inner container, a cover for saidinner and outer containers, said cover comprising a lter and screen forfitting over the top of the inner container to permit flow of theinsulating medium therefrom while retaining the activated earth and aplate in spaced relation to the iilter and screen and secured thereto atits outer edges disposed to cover the containers, the cover having anopening in the screen member to permit the passage of liquids from thespace between the filter and screen and the cover plate to the spacebetween the side walls of the containers, and means for permitting theflow of liquids from the space between the side walls.

7. Apparatus for the reconditioning of liquid insulating mediumscomprising, in combination, an outer container, an inner containerdisposed in spaced relation in the outer container to provide a spacebetween the bottoms and side walls thereof, means for sealing the innercontainer around its bottom to the bottom of the outer container toprovide a space therebetween which is sealed from the space formedbetween the side walls of the containers, means for admitting liquidsinto the sealed space, a screen lter disposed across the bottom of theinner container above the space formed between the bottoms of thecontainers for permitting liquids to flow therefrom into the innercontainer, activated earth disposed within the inner container, a coverfor said inner and outer containers, said cover comprising a filter andscreen for fitting over the top of the inner container and a plate inspaced relation to the lter and screen disposed to cover the containers,the cover having an opening to permit the passage of liquids from thespace between the filter and screen and the cover plate to the spacebetween the side walls of the containers, means for permitting the ow ofliquids from the space between the side Walls, and a pump for deliveringliquid insulating mediums under pressure into the sealed space betweenthe bottoms of the containers to cause it to flow through the lter andupwardly against and through the activated earth thereby agitating theearth and insuring the mixing of the earth with the insulating mediumwhereby the insulating medium is reconditioned, the filter and screen inthe cover permitting the insulating medium to ow from the innercontainer while retaining the activated earth therein.

LOUIS E. SAUER.

